D. Why we just do not cut the paper and insert it in this same direction? Because inserting this paper, with the smaller side to the machine can cause the taletail of the paper to move, which is a more important matter to consider than the fiber.
F. This can make the paper stiffer., so it does not bend when the machine needs it to bend.
Using a wrong fiber direction can make some sheets feelingfeel awkward and stiff. (H)
But regarding covers wrapwarping... yes, it could have adue to wrong fiber direction (I)
but the cases (J) and (K) have the proper fiber direction and the wrappingwarping would still be an issue. This is adue to poor management of the materials more than the fiber direction.
The last issue is regarding folding. On a tri-fold brochure you normally want the fibers to be paralellparallel to the foldingfold. But normally is not that important. Itit is moremore important not to brakeavoid breaking the coating of the paper, handling the paper folding with the right speed on the folding machine.